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Choosing Winch Power

Figure 1: The winch is a rotating lever with the fulcrum of the winch face and force applied by the handle. Internal gearing compounds the leverage. In this case, the advantage is four to one.

Figure 2: The turning block next to the stanchion feeds the line to the winch at a good fair angle. Note the shockcord running from the turning block's becket to the lifeline; this arrangement keeps the block from falling down and fouling when the line is slack.

Figure 3: A self-tailing winch ingeniously eliminates the need for a human tailer. Note that the lead is above horizontal - a wrap is sure to happen.

Winch Definition

Figure1 illustrates the principle of that magnificent rotating lever, the winch. The winch handle is the lever arm, the barrel axis is the fulcrum, and the load is applied at the barrel face. Divide the distance between fulcrum and face into the length of the handle, and the result, in an ungeared winch, is the amount of your advantage.

Internal gearing in two-and three-speed winches in effect lengthens or shortens the lever arm so you can take up slack quickly when the load is light, then switch gears for greater leverage as the load increases.

Fair lead Essential

Several turns with the hauling line around the barrel is the winch equivalent of reeving; the grip of the turns allows force to be applied. The hauling part should form a 95-to-100 degree angle with the winch drum, or a "wrap" (override)—either or both parts becoming bound up in the turns. Very bad news, especially if you need to get the line off the winch in a hurry. When the hauling part's lead isn't fair, a turning block is added between the load and the winch (Figure 2). The tailing part is, well, tailed, either by a crew member or one of a variety of "self-tailing" gizmos (Figure 3).

Efficiently Applied Force

These things are expensive, so you might as well get some performance out of them. To begin hoisting or sheeting-in a sail, leave the handle off for the moment, make your turns (three or four), and begin taking up slack by hand.

Pull with your palms away from you to get a full range of motion as you work your arms in alternation. Keep your hands well away from the winch in case a sudden load slips the turns. When the slack is out, the person with the handle plugs it in and begins cranking while you tail, or you can do both jobs yourself, slowly and carefully with a normal winch, slick as you please with a self-tailing model.

For maximum cranking efficiency, get your weight over the handle and keep it there. Use both hands when possible. When you're running a capstan use a straight-arm, palms-on-handle technique to take up slack, then switch to the low and slow crooked-arm technique as you take a strain.

Winch Size

Sheets can be controlled by blocks alone or by blocks compounded by a winch, depending on how much strain the weather is giving. Running backstays and the halyards for full batten or gaff sails are two more candidates for block-and-winch teamwork. An extra part or two on a purchase means you can go with a smaller winch that will receive less strain.

A modern sail plan comprises a few large, very powerful sails. The intent is to produce greater efficiency and less complexity than the traditional approach of more and smaller sails. But the modern sail plan concentrates forces to such an extent that the winch is the only practicable way to make things work.

In determining adequate winch size, work generated by the sails is the obvious consideration. But work generated in the winch itself is nearly as significant.

How big then does a winch have to be to overcome both the pull of the sails and its own drag? The answer starts with how much effort is acceptable for you. For most people, (15,9 kg (35 pounds) is a comfortable maximum sustained load. Most production boats have maximum loads more like 20 kg (45 lb). That's why it's so hard to sheet that genoa in.

Bear in mind that we're talking about loads that you'll only encounter going to weather in a stiff breeze—a relatively infrequently encountered situation, but one in which boat motion, fatigue, and discomfort hamper physical efforts. It's a situation in which you're most appreciative of adequate mechanical advantage. By investing in a worst-case-scenario power level, you also get extra easy sail handling in lighter airs. A final bonus is that the large drum size means more surface area, and thus more gripping friction on the rope for every turn you make around the drum. So, fewer turns to put on and remove, and better control when easing slack around the drum.

Calculating Winch Power

To calculate desirable sheet winch power, figure your foretriangle area (the area bounded by the forestay, foredeck, and mast); multiply it by 6 (or 29 if you figure your foretriangle area in square meters), a number that accounts for friction and sail force; and divide the answer by 35, your desired maximum input force is 15.9 kg (35 lb). The answer you get will be the rated mechanical advantage in second gear (low gear) of your optimally powered winch.

For example, start with a foretriangle of 28 square meters (300 square feet): 300 x 6=1,800. Divide that by 35 and you get 51.4; you want a winch with about 50:1 advantage. If you felt comfortable with more or less than 15.9 kg (35 lb), your optimum winch would be somewhat less or more powerful.

If you want to know what the maximum handle load on your current winch is likely to be, start with the same Sail Area x 6 (or 29) number, then divide by the rated mechanical advantage through chandlers and manufacturers). The result will be the maximum hand load in pounds (or kg). If we stay with our 28-square-meter (300-square-foot) foretriangle and assume a winch with a typical 40:1 advantage, we get 1,800-40=a typical 45-pound load 795-40=19.9 kg). Too high!

Efficiency Alternatives

If the cost of a big enough winch is too high, or if you're driving a race boat and the extra weight is a consideration, there are four other ways to get more from your winches:

Double-grip handle

Brawn Keep a very large, muscular, and willing individual around to do your winching. This is the traditional option for racing craft. 2. Handle Leverage: A winch is a form of lever, with leverage from internal gearing compounded by leverage from the handle. For example, a(305 mm (12 inch) handle will provide 20% more leverage than the 254 mm (10-inch) handle your winch is probably fitted with now. This advantage is somewhat qualified by the slowness and awkwardness of swinging the handle through a wider arc, but many people hardly notice the difference, and love the ease. Also consider getting a two-hand handle, either 254 mm or 305 mm (10 or 12 inches) long, so you can make better use of the leverage you have, getting the strength of both arms completely into the effort.

Compound AdvantageBy combining a winch with a block and tackle, you compound your mechanical advantage. So a 40:1 winch hooked to a 4:1 block and tackle yields 160:1, minus friction. For quick, coarse take-up at low loads, you can use the block and tackle alone, hooking up the winch for power and refinement. This setup is the rule for mainsheets, but it's not generally a good idea for staysails; blocks hanging from sail clews can be really crew-killing deck floggers. On large traditional boats, with clews well above deck, it's still the viable option that it's always been.

Combine a winch with a block and tackle to compound mechanical advantage.

Another old practice is to put a block on the head of a sail, for a 2:1 advantage, to be compounded by the halyard winch. With a 50% lower load on the winch, you can use a much smaller, cheaper winch. This generates savings that offset even the long-term costs of the 50% longer halyard. These days 2:1 halyards are popular on boats with full-batten mains. The extra power means you can get the sail up faster and with less effort, before putting the halyard on the winch.

Fairleads, Big Blocks, & LubricationBy using a minimum number of large, high-quality, strategically placed turning blocks, you reduce friction. By being one of the minuscule minority of sailors who strip down and lubricate their winches on a regular basis (at least once a year), you reduce friction by a lot more.

Whether your winches have help or work by themselves, protect your investment with regular, careful inspection and maintenance; it's amazing how many people just crank 'em till they freeze up, treating them like convenience items instead of well-bred tools.

Brion Toss—The Complete Rigger's Apprentice

Writer/rigger Brion Toss became obsessed with knots in the late 1960s, a preoccupation that led him to sailing and rigging. He has rigged everything from tiny daysailers to huge square riggers. Equally at home with modern or traditional rigging, Brion continues to pursue the challenge of designing The Ideal Rig—that unique combination of details best suited to a particular boat and its particular crew. Brion has written three books that should be in every sailor's library: The Rigger's Apprentice, Rigger's Locker, and The Complete Rigger's Apprentice. When not writing, Brion can be found at Brion Toss Rigging, his shop in Port Townsend, Washington.